c# How to reference a dynamically created component?

Question

Hi

I have some code that create a few components on the click of a button. Something like this.

CheckBox chk = new CheckBox();
chk.Top = 50;
chk.Left = 50;
chk.Text = "Check Box Test";
chk.Name = "chkTest"
this.Controls.Add(chk);

So how do I use this component. For example I tried this but got and error saying the component didn't exist. I just want to get their values.

if(chkTest.Checked)
{
//Do this
}

Please help.

Thanks in adv.

Answer 1

You're referencing chkTest but you created chk.

Answer 2

You could declare the Checkbox as a member variable of your page. Then you would be able to access it more easily.

Class MyPage { CheckBox chkTest;

// then in page load // chkTest = new CheckBox(); ...

}

Answer 3

Either create a member variable in your class called chkTest that you can use later, or retrieve it on the fly from the Controls collection when needed, like so:

CheckBox chkTest = (CheckBox)Controls["chkTest"];
if(chkTest.Checked) {
    // ...
}

Answer 4

if ((Controls.Items["chkTest"] as CheckBox).Checked)
{
// Do this
}

should work, but it's not pretty to look at. :)

You could declare it as a variable, then use it like you did:

CheckBox chkTest = Controls.Items["chkTest"] as Checkbox;
if (chkTest.Checked)
{
// Do this
}

Look on this handy page for ways to manipulate and access your Control's collection of items: http://msdn.microsoft.com/en-us/library/system.windows.forms.control.controlcollection_members.aspx

Answer 5

If you only care about the control when it is checked or unchecked, use an event.

chk.Checked += new RoutedEventHandler(CheckBox_Checked);
chk.Unchecked += new RoutedEventHandler(CheckBox_Checked);

private void CheckBox_Checked(object sender, RoutedEventArgs e)
{
    CheckBox chkBox = sender as CheckBox;
    if (chkBox.IsChecked.Value)
    {
        // Do this...
    }
}

Make sure to unsubscribe from the event handlers when you are finished with them.